What Buffer, Dissolve, Simplify, Spatial Join, Intersect, Union and Calculate Geometry take and what they return: distances and units, rings, statistics, the nearest feature, and overlays.
Open Everyday vector toolsSix tools do most everyday vector work: Buffer, Dissolve, Simplify, Spatial Join, the two overlays Intersect and Union, and Calculate Geometry. Each has a page under Tools, opens on a layer in the Workspace, and runs from the API with the same parameters. This page says what each one takes and what comes back.
All six follow the same rules as every vector tool: they read the coordinate system your file declares, answer in that system unless you ask for another, and report the same counts. See Coordinate systems in Hyz tools.
Wherever a tool takes a distance, it takes a unit beside it: metres, kilometres, feet or miles. A distance is a distance on the ground. The tool works each feature in a projection that fits that feature, so 500 m is 500 m in Tabuk and in Sharurah, whatever system the file is in.
The limits are fixed on the ground too: a buffer of at most 100 km is 100 km whether you type it in kilometres or in miles.
A buffer draws the area within a distance of each feature. There are three ways to say how far:
| Distance from | What you give | Use it for |
|---|---|---|
| One distance | A number and a unit | A 200 m zone around every school |
| A column | A numeric column of the layer | A pipe buffered by its own width, a well by its own protection radius |
| Rings | Up to 10 distances, such as 100, 250, 500 |
Distance bands: 0–100, 100–250, 250–500 |
ring_from and ring_to. Bands do not overlap. Around a polygon, the first band starts at its edge.Dissolve merges features that share a value into one feature.
sum_population or mean_height. You can ask for sum, mean, minimum, maximum, median, standard deviation, range, the first or last value, the number of distinct values, or a list of them. A count of features is always written, as features.A numeric statistic on a column that holds text is refused, and the message names the column.
Simplify removes vertices that add detail smaller than a tolerance. The tolerance is a distance on the ground.
| Method | What it does | Use it for |
|---|---|---|
| Each feature on its own | Douglas–Peucker, feature by feature | Roads, rivers, coastlines, single outlines |
| Keep shared borders | Simplifies a polygon layer as one, so the border two neighbours share is simplified once | Districts, parcels, any polygons that touch |
Simplifying neighbouring polygons one at a time cuts each side of a shared border differently and leaves slivers and overlaps. Keep shared borders prevents that.
A feature that the tolerance collapses to nothing is left out, and the result counts it as dropped. The result also reports the number of vertices before and after.
A spatial join attaches the columns of a second layer to each feature of the first, by location.
How features are matched
| Relationship | Matches |
|---|---|
| Intersects, Within, Contains, Crosses, Touches, Overlaps | Features of the join layer in that relationship |
| Nearest | The closest feature, with the distance to it. An optional distance limits how far a match may be |
| Within a distance | Every feature within the distance you give |
Nearest and Within a distance write the true distance on the ground in the column distance_m.
How many rows come back
| Rows per input feature | Result |
|---|---|
| One row per match | A feature inside three zones is three rows |
| First match only | One row: the first match, or the closest for a distance |
| Largest overlap | One row: the match it shares the most area or length with |
| Summary of all matches | One row with match_count and the statistics you choose |
zone_. Without one, a name both layers use is told apart as name_left and name_right.The result reports how many input features matched and how many did not.
An overlay cuts two layers by each other. Each piece carries the columns of both features it came from.
| Tool | What comes back | Inputs |
|---|---|---|
| Intersect | The pieces the two layers share | Polygons, lines or points, cut by a polygon layer |
| Union | Every piece of either layer | Two polygon layers |
In a union, a piece only one layer covers has empty values for the other layer's columns.
Pieces keep the dimension of the input: a line cut by polygons stays lines, and two polygons that only share an edge have nothing in common.
Intersect, Clip or Spatial Join?
In the Workspace, picking the whole features that touch a shape is called Select by location.
Calculate Geometry writes what each feature measures into columns. Choose any of:
| Property | Column | Written for |
|---|---|---|
| Area | area_m2, or the unit you choose |
Polygons |
| Perimeter | perimeter_m, or the unit you choose |
Polygons |
| Length | length_m, or the unit you choose |
Lines |
| Centroid position | centroid_lon, centroid_lat |
Every feature |
| Vertex count | vertex_count |
Every feature |
| Part count | part_count |
Every feature |
Areas can be in square metres, square kilometres, hectares, square feet or acres. Lengths can be in metres, kilometres, feet or miles. Area, perimeter and length are measured on the ellipsoid. The centroid is written as longitude and latitude in WGS 84, so it means the same place whatever system the file is in.
If the file already has a column with one of these names, yours is kept and the tool writes its own under a numbered name. The result says so.
Every option here is a field of the tool's request. The tool reference lists each field with its type and limits. Two things to know:
by=["district","use"] and stats=[{"field":"population","op":"sum"}].tolerance in degrees, and Calculate Geometry called with no properties writes the columns Area & Length always wrote.